#2672, fix null handling for ST_AsTWKBagg

git-svn-id: http://svn.osgeo.org/postgis/trunk@12318 b70326c6-7e19-0410-871a-916f4a2858ee
#2670 cleaning some code

git-svn-id: http://svn.osgeo.org/postgis/trunk@12319 b70326c6-7e19-0410-871a-916f4a2858ee
lround should be more correct than round since we expect a long int in return

git-svn-id: http://svn.osgeo.org/postgis/trunk@12320 b70326c6-7e19-0410-871a-916f4a2858ee